Securing device



March 9, 1946! P. B. KELLER ET AL 2,395,651

SECURING DEVICEQ Filed Jan. 15., 1944 PHILIP a xsuze nwewroes' ATTORNEY Patented sacmo navrcn Philip B. Keller, Santa Monica, and Donald .lel-

inelr, Los Angeles, Calla, assignors to North 1 erican Aviation, ind, Los Angeles, ilaliifi, a corporation ofDelawai-e Application January 15, 1944, Serial No. 518,376 2 Claims. (cl. 85-37) This invention relates to securing devices of the composite rivet type wherein a hardened steel rivet pin is provided at one end with an integral head and at its other end with a head formed by swaging a malleable collar around said other end. The primar object of the invention is to provide, in such a composite rivet, a higher tensile loadbearing strength than has been available in prior securing devices of this type.

The further object of the invention is to provide a composite rivet which, although giving increased strength, may be set or formed as easily as the earlier type of composite rivet.

Another object of the invention is to provide a composite rivet which permits the use of a mild steel collar instead of the soft aluminum now employed.

A further object of the invention is to provide a composite rivet having a greater tensile strength than in a standard bolt of the same cross sectional area.

Like reference characters designate similar parts in the several views of the drawing, wherein:

Fig. l is a view, partially in section, of composite rivet embodying our invention, together with parts secured together thereby.

Fig. 2 is a view of the rivet pin and collar assembled with the parts to be secured together,

before attachment of the collar to the pin.

Fig. 3 is a view showing the final relationship between the rivet pin and the setting tool with the collar, in its original shape, indicated in broken lines.

Fig, 4 is a view of a modified form of the rivet pin.

As an example of one form inwhich the invention may be embodied, We have shown in the drawing a composite rivet including a hardened pin Ill, preferably of steel, adapted to be ex tended through aligned openings H and 12 in a pair of members is and it to be securedtogether, having at one end an integral head l5 adapted to engage one of the members l3, I l, and having at its other end a grooved end portion l6 adapted to project beyond the member it, M, and to be secured by a collar I l.

The collar H is of malleable material and is impressed into a series of grooves ill in the end portion it of the pin, forming annular teeth E9 in the collar which intermesh with the annular teeth 20 defined'in the pin by the grooves 18.

In prior composite rivets of this general type, a single relatively deep groove is employed, and the collar is of soft aluminum in order that it may be pressed into such relatively deep groove. In the present invention, instead of the single groove, we provide a series of relatively shallow grooves. Consequently, less deformation of the collar is required in order to fill the groove, and We therefore find it possible to form the collar of mild steel, which is considerably stronger than aluminum.

The groove l8 are made progressively deeper toward the end of the pin. Thus there is a minimum weakening of the pin in the central region thereof where the full tension load is carried, and the weakest section of the pin is at the outer end where the minimum tension load is carried.

A maximum increment of load is transferred to the pin from the collar at the outer end of the pin, and the increments of load transferred to the pin from the collar successively decrease toward the base of the tier of grooves. Since each succeeding cross section of the pin at the bottoms of the grooves 58, however (proceeding from the outer end of the pin toward the head), carries the accumulated load transmitted to the preceding teeth of the pin, there is a proper balance between the loads transmitted from the succeeding teeth IQ of the collarto the coacting teeth 20 of the pin and the loads transmitted successively from one cross section to another of the pin.

The collar H in its initial form, shown in Fig. 2, is a plain cylindrical ring. It is forced into the grooves ill by applying axial pressure from a setting tool 2| while supporting the head of the rivet pin with a bucking bar 22. The setting tool 2| has an interior frusto-conical surface 23 which forces the collar radially inwardly as the tool is moved axially toward the. pin. At the end of the setting strok the tool assumes the position shown in Fig. 3. Because of the conical shapeof the surface 23, the base region of the collar is forced inwardly only slightly while the outer region is forced inwardly a maximum distance. The progressively increasing depth of the grooves l8 accommodates the progressively greater compression of the collar toward its outer end. Consequently, ther is practically no axial flow of the metal of the collar during the initial setting opminum and yet the amount of pressure required for setting the rivet is not substantially greater than that required in setting the aluminum collar of the earlier type of rivet.

I The teeth 20 in their original form shown in Fig. 2 lean toward the end or the rivet pin as indicated. During the setting operation, however, and after the grooves are filled the com- 1 ponent of force exerted downwardly by the setting tool upsets the teeth axially until they lean toward the head of the rivet as shown in Fig. 1-. This increases the buttressing effect and gives greater load-bearing capacity in the transfer of loads from the collar to the pin.

By employing a forming surface 23 that is frusto-conical, it is possible for the tool to be easily pulled away from the rivet after the head has been formed thereon. Thus it will be seen that the conical shape of the head and the progressively decreasing depth of the grooves I8 cooperate to produce a number of desirable results.

Instead of a pluralitgwf teeth and grooves, we

may employ a thread defining a continuous groove of increasing depth toward the end or the pin, as

shown in Fig. 4, without departing from the scope of the invention as defined in the appended claims. e

The cross sectional area of the teeth 20 is r' later: to that of the teeth 19 in the ratio of the shear strength of the pin material to that of the collar.

We claim as our invention:

1. For attaching together a pair of members having aligned openings, a securing device com-' prising a hardened pin extendable through said openings, having at one end a head adapted to engage one of the members and at its other end a grooved portion projecting beyond themembers, said grooved. portion being provided with a plurality of grooves, and a collar of relatively soft malleable material adapted to encircle said grooved end and to be compressed into said grooves,v said grooves defining a plurality of teeth which, in axial cross section, lean toward the head of said pin as a result of axial pressure transmitted to them through the collar from a forming tool during assembly thereof.

2. A device for attaching together a plurality of members having aligned openings therethrough, including a hardened pin extendable through such aligned openings, and having a headed portion for engaging one side of the assembled' members, a plurality of grooves adja- 

